She should probably get them to the vet asap, they are young and there is no knowing how long they were left without mum, food and water.
I'd possibly be trying to syringe water into the little one too, might be very dehydrated (I'm assuming it's probably quite warm out there which would exacerbate any dehydration issues?).
She should probably make sure they are flea free too which is another thing to sap the life out of young kittens.
I'm not sure how old they are when they start toileting by themselves and whether she needs to rub their bottoms to encourage still?
I'd be beside myself if i had such an unresponsive baby so can imagine how she's feeling.